This invention pertains generally to a method that aids in harvesting crops by application to the crop of a certain compound prior to harvest, so as to cause crop defoliation or vine dessication. More specifically it pertains to a method that aids in harvesting crops, particularly cotton or potatoes, by application of an alkyl 2-(5-ethyl-2-(4-(1-methyl-6-trifluoromethyl-2,4-(1H, 3H)-pyrimidinedion-3-yl)phenoxymethyl)phenoxy)propionate.
It is well known that the harvesting of certain crops may be aided by the use of substances that cause crop defoliation or vine dessication. For example, cotton defoliation prior to harvest has several potential benefits. The removal of leaves (1) eliminates the main source of stain and trash, resulting in better grade cotton, (2) allows the cotton picker to operate faster and more efficiently, (3) allows quicker drying of dew so that picking can start earlier in the day, (4) helps straighten lodged plants for more efficient picking, (5) retards boll rot, and (6) helps stimulate boll opening. How well the cotton defoliates will often effect the yield and fiber quality of the cotton. (K. Edmisten, Center for Integrated Pest Management, North Carolina State University, via internet publication dated March, 1995).
For the harvesting of vine crops such as potatoes, vine desiccation is desired. Potatoes on dessicated vines are easier to harvest than those on living vines. In addition, potatoes on the killed vines are less likely to skin and bruise during harvesting. Where skinning occurs, the skinned areas of a potato are susceptible to discoloration and soft rot infection. Furthermore, skinned potatoes lose weight more rapidly and appear untidy.
Examples of compounds that are commonly used as cotton defoliants include S,S,S-tributyl phosphorotrithioate, also known as butifos or Def.RTM., and 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea, also known as thidiazuron or Dropp.RTM.. Compounds that are commonly used for potato vine desiccation are 1,1'-ethylene-2,2'-bipyridyldiylium ion as the dibromide monohydrate salt, also known as diquat, (+/-)-2-amino4-(hydroxymethylphosphinyl)butanoic acid, also known as glufosinate, and 1,1'-dimethyl-2,2'-bipyridyldiylium ion as the dichloride salt, also known as paraquat. Among the limitations of some of these commonly used harvest aids is the need for high use rates. Thus, there is a continuing demand for new substances that promote crop defoliation or vine desiccation at low use rates and in a safe manner.
U.S. Pat. No. 5,344,812 (Theodoridis) describes herbicidal compounds having the formula ##STR2## in which A is a derivative of an alkanoate bonded to the phenoxy oxygen at the alpha carbon; Q is one of several heterocyclic rings; X is hydrogen, methyl, fluorine or chlorine; Y is hydrogen; W is oxygen or sulfur; Z is hydrogen, fluorine, chlorine, bromine, lower alkyl, or methoxy; and Z' is hydrogen, fluorine, or chlorine. When applied as postemergence herbicides these compounds were reported to exhibit very good control of a variety of weeds, but with no crop tolerance. Thus the compounds were considered excellent candidates as total vegetation control agents. The utility of these compounds as a harvest aid by causing crop defoliation or vine desiccation has not been reported.